question on SAP AMDP classes

Hi,

I am new to sap SQL script, I want to fetch data from HDB using AMDP method.

In a class implementation I am writing SQL SCRIPT  as

ET_VBKAP = SELECT a.vbeln , a.vkorg , a.vtweg , a.spart , a.kunnr ,  b.posnr , b.matnr , b.matwa from vbak as a inner join vbap as b

                                    on a.vbeln  = b.vbeln.

now I want to get Customer details from KNA1 tale based on ehtries in ET_VBKAP tale please suggest

et_kna1  =  select kunnr name1 name2 land1 from kna1 ???????????????????????... what I need to write to fetch entries based on entries in ET_VBKAP table.

Thanks,

RG